The brain performs the most important functions in the human body and is the main organ of the central nervous system. When its activity is stopped, even if breathing is maintained with the help of artificial lung ventilation, doctors ascertain clinical death.
Anatomy
The medulla oblongata is placed in the posterior cranial notch and looks like an inverted bulb. From below, through the occipital foramen, it connects to the spinal cord, from above it has a common border with the pons. Where the medulla oblongata is located in the cranium is clearly shown in the picture posted later in the article.
In an adult, the organ in its widest part is approximately 15 mm in diameter, in full length it reaches no more than 25 mm. Outside, the medulla oblongata envelops the white matter, and inside it is filled with gray matter. In its lower part there are separate clots - nuclei. Through them, reflexes are carried out, covering all body systems. Let's take a closer look at the structure of the oblongbrain.
Outer part
The ventral surface is the outer anterior part of the medulla oblongata. It consists of paired cone-shaped lateral lobes, expanding upward. The departments are formed by pyramidal tracts and have a median fissure.
The dorsal surface is the posterior outer part of the medulla oblongata. It looks like two cylindrical thickenings, separated by a median sulcus, consists of fibrous bundles that connect to the spinal cord.
Interior
Let's consider the anatomy of the medulla oblongata, which is responsible for the motor functions of skeletal muscles and the formation of reflexes. The core of the olive is a sheet of gray matter with jagged edges and resembles the shape of a horseshoe. It is located on the sides of the pyramidal parts and looks like an oval elevation. Below is the reticular formation, consisting of plexuses of nerve fibers. The medulla oblongata includes the nuclei of the cranial nerves, centers of respiration and blood supply.
Kernels
Glossopharyngeal nerve contains 4 nuclei and affects the following organs:
- throat muscles;
- palatine tonsils;
- taste receptors on the back of the tongue;
- salivary glands;
- tympanic cavities;
- Estachian tubes.
The vagus nerve includes 4 nuclei of the medulla oblongata and is responsible for the work:
- abdominal and chest organs;
- muscles of the larynx;
- Auricle skin receptors;
- internal abdominal glands;
- neck organs.
Accessory nerve has 1 nucleus, controls the sternoclavicular and trapezius muscles. The hypoglossal nerve contains 1 nucleus and affects the muscles of the tongue.
What are the functions of the medulla oblongata?
The reflex function acts as a barrier against the ingress of pathogenic microbes and external stimuli, regulates muscle tone.
Defensive reflexes:
- When too much food or toxic substances enter the stomach, or when the vestibular apparatus is irritated, the vomiting center in the medulla gives the body a command to empty it. When the gag reflex is triggered, the contents of the stomach exit through the esophagus.
- Sneezing is an unconditioned reflex that removes dust and other irritating agents from the nasopharynx by rapid exhalation.
- The secretion of mucus from the nose performs the function of protecting the body from the penetration of pathogenic bacteria.
- Cough is a forced exhalation caused by the contraction of the muscles of the upper respiratory tract. Clears the bronchi from phlegm and mucus, protects the trachea from foreign objects getting into it.
- Blinking and tearing are protective reflexes of the eyes that occur upon contact with foreign agents and protect the cornea from drying out.
Tonic reflexes
The centers of the medulla oblongata are responsible for tonic reflexes:
- static: body position in space, rotation;
- statokinetic: installation and rectifyingreflexes.
Food reflexes:
- excretion of gastric juice;
- sucking;
- swallowing.
What are the functions of the medulla oblongata in other cases?
- cardiovascular reflexes regulate the work of the heart muscle and blood circulation;
- respiratory function ensures ventilation of the lungs;
- conductive - is responsible for the tone of skeletal muscles and acts as an analyzer of sensory stimuli.
Symptoms of the lesion
The first descriptions of the anatomy of the medulla are found in the 17th century after the invention of the microscope. The organ has a complex structure and includes the main centers of the nervous system, in case of violation of which the whole organism suffers.
- Hemiplegia (cross paralysis) - paralysis of the right arm and left lower half of the body or vice versa.
- Dysarthria - limited mobility of the organs of speech (lips, palate, tongue).
- Hemianesthesia - decreased sensitivity of the muscles of one half of the face and numbness of the lower opposite part of the trunk (limbs).
Other signs of medulla oblongata dysfunction:
- mental arrest;
- unilateral paralysis of the body;
- impaired sweating;
- memory loss;
- paresis of facial muscles;
- tachycardia;
- reduced lung ventilation;
- retraction of the eyeball;
- pupil constriction;
- inhibition of the formation of reflexes.
Alternating syndromes
Study of the anatomy of the medulla oblongata showed that when the left or right side of the organ is damaged, alternating (alternating) syndromes occur. Diseases are caused by a violation of the conduction functions of the cranial nerves on the one hand.
Jackson Syndrome
Develops with dysfunction of the nuclei of the hypoglossal nerve, the formation of blood clots in the branches of the subclavian and vertebral arteries.
Symptoms:
- paralysis of the muscles of the larynx;
- impaired motor response;
- tongue paresis on one side;
- hemiplegia;
- dysarthria.
Avellis Syndrome
Diagnosed with damage to the pyramidal regions of the brain.
Symptoms:
- paralysis of the soft palate;
- swallowing disorder;
- dysarthria.
Schmidt Syndrome
Occurs with dysfunction of the motor centers of the medulla oblongata.
Symptoms:
- trapezius paralysis;
- vocal cord paresis;
- incoherent speech.
Wallenberg-Zakharchenko Syndrome
Develops when there is a violation of the conductive ability of the fibers of the muscles of the eye and dysfunction of the hypoglossal nerve.
Symptoms:
- vestibular-cerebellar changes;
- paresis of the soft palate;
- reducing facial skin sensitivity;
- skeletal muscle hypertonicity.
Glick Syndrome
Diagnosed with extensive damage to the brain stem and nuclei of the medulla oblongata.
Symptoms:
- decreasevision;
- spasm of facial muscles;
- swallowing disorder;
- hemiparesis;
- pain in the bones under the eyes.
The histological structure of the medulla oblongata is similar to that of the spinal cord; when the nuclei are damaged, the formation of conditioned reflexes and motor functions of the body is disturbed. To determine the exact diagnosis, instrumental and laboratory studies are carried out: brain tomography, cerebrospinal fluid sampling, skull radiography.
